Device for conducting crushing and screening operations simultaneously



Sept. 9, 1969 z. ARDARY 3,455,972

DEVICE FOR CONDUCTING CRUSHING AND SCREENING OPERATIONS SIMULTANEOUSLYFiled May 10, 1967 INVENTOR. Zane L. Ardary BY MQ.MM

.ATTORNE Y.

United States Patent US. Cl. 241-69 1 Claim ABSTRACT OF THE DISCLOSURE Ahollow cylinder into which is placed a material to be crushed is mountedfor rotation about its longitudinal axis. Crushing action is provided bya solid metal rod disposed inside the cylinder. As the cylinder rotates,the bar is picked up by a pair of dogs at the bottom of the cylinder anddropped from the top, thereby crushing any material caught between thebar and the wall. A portion of the wall of the cylinder is made of aselected size screen so that on each revolution of the cylinder thecrushed material falls through the screen into a receptacle and is notleft in the cylinder to produce fines from subsequent crushings. Thisdevice is quite useful in situations where it is desirous to obtain anarrow screen fraction of crushed particles in a very economical manner.

BACKGROUND OF THE INVENTION This invention relates to crushing andscreening devices and more specifically to a low energy rotary crushingand screening device in which the material to be crushed is rotated in acylinder together with a crushing element and screening takes place oneach revolution of the cylinder.

This invention was made in the course of, or under, a contract with theU. S. Atomic Energy Commission.

When preparing spheroidal particles of uranium dicarbide for use inreactor fuel applications, one process comprises suspending uraniumdicarbide particulates of -325 mesh in a carbon black matrix andapplying sufficient heat to melt the uranium dicarbide. It has beenfound that, if the uranium dicarbide particulates are pre-sized to anarrow fraction prior to admixing with the lamp black, the yield of thedesired size fraction in the product is increased.

The problem arises of how to economically obtain a high yield of anarrow screen fraction of uranium dicarbide particulates. The usualmilling procedures and equipment will effectively reduce relativelylarge pieces of uranium dicarbide to small pieces through the action ofcrushing. However, the prior art mills and crushers utilize attritionextensively in conjunction with crushing. One result is the productionof large quantities of fines. Further, since the prior art mills and thelike produce particles varying in size over a large range, to obtain anarrow screen fraction one must crush, screen, and recharge the largeparticles to the crusher for further reduction in size. The obviousdisadvantage is excessive labor and expense.

SUMMARY OF THE INVENTION The present invention is a mechanical devicewithin which the dual functions of crushing and screening are performedand comprises a hollow cylinder rotatable about an axis disposed in ahorizontal plane, means rotating the cylinder on its horizontal axis,passageway means penetrating a predetermined portion of the wall of thecylinder for conveying material below a predetermined size from thecylinder when the passageway means are in a lowermost locationunderlying the axis of the cylinder, material crushing means disposed inthe cylinder for Patented Sept. 9, 1969 ice crushing material againstthe inner side wall of said cylinder, and means disposed in the cylinderfor lifting the crushing means out of contact with the wall when saidpassageway means are in a lowermost location and for releasing thecrushing means to effect crushing when said passageway means are rotatedout of the lowermost location.

Accordingly, it is an object of this invention to provide a device forperforming the dual functions of crushing and screening and forfacilitating product removal after a minimum energy input to minimizefines generation.

Other objects and many of the attendant advantages of the presentinvention will become evident from the following description when takenin conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIGURE 1 is a schematic representationof a crusherscreener according to the present invention; and

FIGURE 2 is an enlarged, cutaway view of the cylinder element of FIGURE1.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIGURE 1, there isshown a hollow cylinder 5 closed at its ends by removable plates 7 and9. Cylinder 5 is rotatably mounted in a horizontal plane by, and infrictional contact with, a pair of rollers 11 and 13. Rollers 11 and 13are rotatably mounted on a frame assembly 15. A motor 17 is provided onframe 15 for driving roller 11 through a belt assembly 19, hencerotating cylinder 5.

For atmospheric control purposes, a housing 21 is pro vided having anupper hood portion 23 and a tapered portion 25 which extends downwardbelow the cylinder for directing screened product into a receptacle 27.

Referring now to FIGURE 2, details of the construc tion of cylinder 5are shown with plates 7 and 9 removed. A portion of the wall 29 of thehollow cylinder 5 comprises a screen 31 extending approximately theentire length of the wall but only extending over less than aboutone-half of the circumference thereof. Assuming clockwise rotation ofcylinder 5, as shown in FIGURE 2, a pair of dogs 33 and 35 are providedon wall 29 at the leading edge of screen 31. Within the cylinder 5, aheavy solid rod 37 is provided as a crusher. Dogs 33 and 35 aregenerally L-shaped so that as the cylinder rotates rod 37 comes incontact with the dogs at the bottom of the cylinder and lifts the rod.

In operation, an appropriate amount of material to be crushed is loadedinto cylinder 5 and as cylinder 5 rotates clockwise, dogs 33 and 35 pickup rod 37 at or near the bottom of cylinder 5 near the leading edge ofscreen 31, carry it in an arcuate path upward as the cylinder continuesto rotate, and, as the dogs reach their uppermost position, the rodrolls off and falls to the bottom of the cylinder, crushing any materialcaught between the falling rod and the bottom portion of the cylinderwall. Preferably, the rod 37 is held by the dogs until the screen 31 haspassed the lowermost position before the rod is dropped so that thescreen at no time is subjected to the weight of the crusher rod or toits impact upon its falling from the dogs.

As cylinder 5 continues to rotate, the dogs again lift rod 37 at theleading edge of the screen. The screen now comes into the lowermostposition and those particulates which are small enough fall through thescreen into receptacle 27.

During each revolution of cylinder 5 there is a single crushing impactby the crusher rod and sized particulates are extracted. Due to thecrushing and subsequent screening during each revolution a minimumamount of attrition occurs because the rod rolls upon the particles overonly a short distance and the sized particles areextracted from thecylinder before significant attrition can occur. It should be noted,too, that the vibration creaed When the falling rod strikes the cylinderserves to clean the screen.

As an example, a typical crushing operation employed an S-inch-diametercylinder, 14 inches long, having a SO-mesh screen covering 71 degrees ofthe cylinder surface and an 8-pound crusher rod. At a cylinder speed of100 r.p.m., uranium dicarbide chunks of approximately Ar-inch diameterwere crushed to produce 7 pounds per hour of particles, 40 weightpercent of which were Within a desired 60 to 100 mesh range.

It will be seen that aunitary device is provided which performs the dualfunctions of crushing and screening with a minimum energy input whichreduces fines gen eration and produces a high yield of a narrow screerfraction of particulates.

It will be understood that, while the preferred embodiment has been setforth, the invention is not limited thereto and various modificationsmay be made without departing from the spirit and scope of the inventionas set forth in the appended claim.

What is claimed is:

1. A material crushing and screening device into which material to becrushed is loaded prior to operation, comprising: a hollow cylinderenclosed at the ends disposed for rotation with its longitudinal axisessentially horizontal; means for rotating said cylinder about itslongitudinal axis, said cylinder having an opening longitudinallyextending over substantially the length of said cylinder and extendingcircumferentially over less than half of the circumference of saidcylinder; a screen having a predetermined mesh size disposed in saidopening; a crushing rod disposed within said cylinder, said rod beingsubstantially coextensive with the interior length of said cylinder; apair of dogs mounted on said cylinder wall adjacent the leading edge ofsaid opening, accor ing to the direction of rotation of said cylinder,said dogs having a configuration such that they engage said rod at aposition underlying the longitudinal axis of said cylinder and lift saidrod in an arcuate path upward upon each revolution of said cylinder to aposition near the top of said cylinder where said rod is dropped so asto strike the material being crushed at a position on the underlyingcylinder Wall adjacent the trailing edge of said opening.

References Cited UNITED STATES PATENTS 639,406 12/1899 Kreiss 241-91741,606 10/1903 Zarniko 24l176 ROBERT C. RIORDON, Primary Examiner M.RASKIN, Assistant Examiner US. Cl. X.R. 241101, 178

